<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.0/jquery.js"></script>
<title></title>

</head>
<body>
	<div id="app">
		<span>用户名:</span><input>
		<br/>
		<br/>
		<!-- <span>邮&nbsp;&nbsp;&nbsp;箱:</span><input> -->
		<span>邮箱名:</span><input>
		<br/>
		<br/>
		<span>手机号:</span><input>
	</div>
<script>
	$(function(){
		$('input').focus(function(){
			//焦点出现字
			$(this).after(`
			<span>请按要求输入</span>
			`);
			// $(this).after('1111');
			// console.log(this)
			//失去焦点
		}).blur(function(){
		$(this).next().remove();
			// console.log($(this).next().remove())
			$(this).after(`<span>不可为空</span>`);
		})
		
		
		// console.log($('input'))
		
	})
</script>
</body>
</html>
